For example, if you are aiming for 100% and you get -- say -- 98% in one exam, you won't really care because you were aiming for 100% and that 2% is enough for you to disregard everything and any ambition of aiming the highest even though it probably won't make a difference in the long run.
i.e. You want something to be completely perfect ELSE you don't care for it at all.